Fire Sprinklers

As the name suggests this is a fire sprinkler system fed directly by the town water main. As such there is no need to store the water in a tank or pump the water around the system. However a town water main fire sprinkler system is reliant on the consistency of water pressure provided by your local utility company.

To feed a fire sprinkler system the water main must satisfy the following criteria:

1. There must be a dedicated* 32-50mm (cat 1), 50mm (cat 2), 50-63mm (cat 3) incoming water main into the property.
2. The water main must be unmetered – this is a requirement of the British Standard.
3. Water pressure and flow must be determined by the design and hydraulic calculation, typically between 2.5 and 4 bar
4. The water flow rate varies between litres per minute (Cat 1, 1 head) and 240 litres per minute (Cat 3, 4 heads).

If the town water mains supply in your building can not meet these criteria and a new supply is not an option then a stored water supply should be used.

 Pump and Tank Fire Sprinklers – this system is fed from water stored in a tank and pumped to the sprinklers.

Ultrasafe offer servicing, testing, maintenance and servicing on all our fire sprinkler systems for more information please go to our page on Servicing and Maintenance of Fire Sprinklers.

*If a dedicated supply cannot be provided then a priority demand (solenoid) valve can be fitted. This will divert water to the fire sprinkler system upon activation. However, an additional 25 litres per minute will be required on top of the design duty.

Pump & Tank Fire Sprinkler Systems

Fire sprinkler tank & self testing pump

If the town water main does not meet the criteria cannot then your sprinkler system will need to be fed from a stored water supply. From here we attach a self-testing pump to ensure that the required water can be supplied to all the sprinkler heads. 

Fire sprinkler tank size calculations

The size of the tank is designed by the hydraulic calculations of the system using the number heads determined by the category. BS9251:2014 states typical volume of tanks as Cat 1 1500 litres, Cat 2 3000- 4500 litres and Cat 3 6000-9000 litres.

Should a tank have a proven infill (through a 32mm @ over 1.2 litres per second (cat 1) 50mm (cat 2-3) @ 2 litres per second) then the water storage capacity could be reduced by 40% assuming building control are satisfied with this.

Existing water tanks can be used assuming that the above volumes can be guaranteed for the use of the sprinkler system. A boosted mains water supply system can also be utilised if sufficient water storage is available.

The image shows a domestic water tank and self-testing pump. This system will provide the building with a 10 minute operational run time. (In residential installations the system will provide the building with a 30 minute operational run time).